Due to actualization of environmental problems in recent years, hybrid cars and electric cars have spread. Furthermore, as an air-conditioning device which is applicable to such a vehicle, there has been developed an air-conditioning device which comprises a compressor to compress and discharge a refrigerant, a radiator (a condenser) disposed on a vehicle interior side to let the refrigerant radiate heat, a heat absorber (an evaporator) disposed on the vehicle interior side to let the refrigerant absorb heat, and an outdoor heat exchanger disposed outside the vehicle interior to let the refrigerant radiate or absorb heat, and which changes and executes respective modes, i.e., a heating mode in which the refrigerant discharged from the compressor radiates heat in the radiator and the refrigerant by which heat has been radiated in this radiator absorbs heat in the outdoor heat exchanger, a dehumidifying mode in which the refrigerant discharged from the compressor radiates heat in the radiator and the refrigerant by which heat has been radiated in the radiator absorbs heat in the heat absorber, and a cooling mode in which the refrigerant discharged from the compressor radiates heat in the outdoor heat exchanger and absorbs heat in the heat absorber (e.g., see Patent Document 1).
Additionally, in Patent Document 1, there is disposed an injection circuit which distributes the refrigerant flowing out from the radiator, decompresses this distributed refrigerant, and then performs heat exchange between the decompressed refrigerant and the refrigerant flowing out from the radiator to return the refrigerant to the middle of compression by the compressor, thereby increasing an amount of the refrigerant to be discharged from the compressor and improving a heating qualification by the radiator.
In addition, there has also been developed an air-conditioning device which executes respective operation modes of a heating operation in which a refrigerant discharged from a compressor radiates heat in a radiator and the refrigerant by which heat has been radiated in this radiator absorbs heat in an outdoor heat exchanger, a dehumidifying and heating operation in which the refrigerant discharged from the compressor radiates heat in the radiator and the refrigerant by which heat has been radiated in the radiator absorbs heat only in a heat absorber or in this heat absorber and the outdoor heat exchanger, a cooling operation in which the refrigerant discharged from the compressor radiates heat in the outdoor heat exchanger and absorbs heat in the heat absorber, and a dehumidifying and cooling operation in which the refrigerant discharged from the compressor radiates heat in the radiator and the outdoor heat exchanger and absorbs heat in the heat absorber (e.g., see Patent Document 2).